Particle filter and method for the purification of an exhaust-gas flow

Abstract

Particle filters and a method for the purification of an exhaust-gas flow are described. In one example, exhaust gas is directed solely to a first particulate filter until a predetermined condition. Then exhaust gas is directed to a second particulate filter. One particulate filter may surround the other of two particulate filters. The particulate filters may provide filtered exhaust gas even when one filter becomes at least partially loaded.

Description

RELATED APPLICATIONS[0001]The present application claims priority to German Patent Application No. 102011003019.0 filed on Jan. 24, 2011, the entire contents of which are hereby incorporated by reference for all purposes.FIELD[0002]The description relates to a particle filter and to a method for the purification of an exhaust-gas flow. In particular, the description relates to the purification or filtering of exhaust gases of an internal combustion engine of a motor vehicle.BACKGROUND AND SUMMARY[0003]Particles, such as for example carbonaceous soot, generated during the combustion of fuels may be retained by a filter in order to reduce the exhaust-gas emissions. For this purpose, the exhaust-gas flow passes through a filter in which the particles accumulate. A periodic regeneration of the filter is necessary in order to reduce the particle loading and to ensure a controlled level of the exhaust-gas counterpressure.[0004]In the event of the filter approaching a storage capacity, the...

AI Technical Summary

Benefits of technology

[0007]The possibility of increasing vehicle emissions may be reduced by providing a secondary exhaust path around a first particulate filter during conditions in which particulate matter stored in a first particulate filter approaches a storage capacity of the first particulate filter. Specifically, during conditions where particulate matter stored in the particulate filter is less than a threshold amount, exhaust gases may be directed substantially solely to the first particulate filter to save or maintain particulate matter storage capacity in a second particulate filter. However, when particulate matter stored in the first particulate filter exceeds the threshold level, a second exhaust path may be enabled, the second exhaust path directing exhaust gases to the second particulate filter. In this way, engine exhaust back pressure may be reduced until the first particulate filter is regenerated or replaced.

[0008]The present description may provide several advantages. In particular, the approach may improve engine emissions by increasing the exhaust filtering capacity of the vehicle exhaust system. In addition, the approach may extend the time between vehicle service intervals and or particulate filter regeneration. Further, in some examples, the approach may be implemented in a cost effective configuration which may not include an electrically controlled exhaust gas routing system.

Problems solved by technology

In the event of the filter approaching a storage capacity, the increased exhaust-gas counterpressure may have an adverse effect on the performance of the engine.

Furthermore, in the case of a high soot loading, the exothermic heat generated during particulate filter regeneration may degrade parts of the exhaust system.

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